For competitive athletes, travel is often built into the sport itself. A world championship, a destination marathon, or a training camp can mean crossing several time zones, adjusting to a new climate, and then racing on a body that just spent a full day in transit. A review published this year in the Journal OF Sports Medicine looked at the current science on how travel affects athletes and what can be done about it. While much of the underlying research comes from professionals and elites, the practical lessons translate well to any athlete traveling for a big event.
THE TWO ISSUES ENCOUNTERED
Two separate problems get lumped together. Jet Lag and Travel Fatigue. Let’s explore both of these. Jet lag is the mismatch between an athlete's internal body clock and the local time at the destination. This shows up when crossing time zones. Travel fatigue, on the other hand, is the general toll of the trip itself, including hours of sitting, disrupted routines, dehydration, and the stress of unfamiliar logistics. Travel fatigue can happen on any long trip, even one that does not cross a time zone, and it compounds whatever jet lag is also present. Both are associated with worse sleep, mood, reaction time, and decision-making.
“It's estimated that the body's internal clock adjusts by roughly 1 hour per day.”
Direction of travel matters as much as distance. Eastward travel tends to be harder on the body than westward travel, because advancing the internal clock earlier is a bigger physiological ask than delaying it. In practical terms, flying to a race in Europe from the US will likely take more days to adjust to than flying home afterward, so it makes sense to weigh travel planning toward extra days prior to competition rather than splitting the days evenly around the race.
An athlete’s natural tendency toward morning or evening alertness may also shape how travel is tolerated. While not definitive, naturally early risers may adapt somewhat more easily to eastward travel and early competition starts, while naturally late risers may fare better with westward travel and later start times. This is not something to overhaul travel plans around, but it can help explain why two training partners on the same flight sometimes report very different adjustment experiences.Travel also appears to carry a real health cost beyond fatigue and sleep disruption.
“Athletes traveling to destinations more than five time zones away have been found to face two to three times the normal risk of illness in the week after arrival.”
Mostly upper respiratory infections picked up in crowded airports, terminals, and cabins. Hygiene habits that lower this risk include frequent handwashing, staying current on routine vaccinations, avoiding buffet-style dining when possible, and getting enough sleep. Soft tissue injuries are harder to tie directly to travel in the research, but there is a correlation between short sleep and injury risk in general, which is one more reason to protect sleep around a big trip.
HYDRATION MATTERS
Hydration serves as a specific area of focus on travel days. Cabin air is dry, and cabins are pressurized to roughly the equivalent of 8,000 feet of altitude, both of which increase fluid losses during a flight. Studies simulating long-haul flights have found measurable reductions in plasma volume, driven more by fluid shifting toward the legs than by athletes losing meaningful body mass. A reasonable target during a flight is between 100 and 300 mL/fluid per hour, adjusted for personal tolerance, flight length, and the climate at the destination. Alcohol works against all of this by increasing fluid losses and disrupting sleep, so it is one of the things to skip on travel days. Moderate caffeine intake does not cause dehydration, though it is still worth avoiding it in the hours before sleep while the body is trying to adjust to a new schedule.
“More than half of international travelers report some gastrointestinal symptoms during or shortly after a trip.”
Circadian disruption can slow digestion and shift the timing of enzyme secretion. Favoring familiar, easily digestible foods before and during flights, choosing smaller and more frequent meals over large ones, can all reduce the odds of gastrointestinal issues.
LIGHT IS IMPORTANT
Light exposure is incredibly helpful in resetting the body clock. The right timing depends on the direction of travel and how many time zones were crossed, so a blanket rule like getting outside first thing in the morning does not always apply. After eastward travel, bright light earlier in the day tends to help shift the clock forward, while after westward travel, bright light later in the day tends to help shift it back.
“Naps of 20 to 90 minutes, taken in the early to mid-afternoon, can offset some accumulated sleep debt without impairing nighttime sleep.”
Exercise can also be beneficial, so a well-timed easy session can be a useful complement to light exposure in the days after arrival.
MELATONIN & CAFFEINE - KNOW WHAT YOU NEED
Both melatonin and caffeine are frequently discussed when managing jet lag. Melatonin is a hormone produced mainly by the pineal gland. Production rises in the dark and falls with light exposure. When taken at the right time, it can nudge the circadian rhythm earlier or later. The timing of a dose matters more than the dose size specifically for jet lag. However, in the US, melatonin is a supplement, and the FDA does not evaluate the safety, effectiveness, or accuracy of labels before supplements reach consumers. A 2017 study analysis of 31 commercial melatonin products found that melatonin content fell short of or exceeded the labeled amount by more than 10 percent in most products.
“The actual melatonin content ranged from 83 percent below to 478 percent above what the label claimed”
Additionally, they found substantial lot-to-lot variation within single products, meaning two bottles of the same brand were not guaranteed to contain matching doses. For these reasons, athletes need to be extremely cautious if they decide to take these products and opt for NSF Certified for Sport or Informed Sport certified products. A low dose of about 0.3 to 1.0 milligrams, taken two to four hours before the target bedtime, may be beneficial, though researchers note that optimal dosing specifically for athletic populations has not been fully established.
Caffeine works through a different pathway, blocking adenosine receptors to reduce tiredness, and therefore can be useful to manage travel fatigue. In research, a single dose of 300 mg slow-release caffeine enhanced alertness and reduced daytime sleepiness. Notably, the timing of caffeine is important. Caffeine taken in the evening or in the hours before planned sleep can delay sleep onset and worsen the circadian misalignment an athlete is trying to resolve.
PUTTING TOGETHER A TRAVEL PLAN
Surviving international travel and racing well after it are two different challenges, and the most effective preparation needs to cover the basics first before fine-tuning the extra details that may make a quarter-percent difference.
Frequent handwashing and illness prevention are the top priorities for every athlete. When it comes to managing the travel itself, the basic preparation includes:
- arriving at the airport already well hydrated with appropriate snacks,
- drinking roughly 100 to 300 mL of fluid per hour during the flight itself,
- skipping alcohol,
- moving periodically rather than sitting the entire way, and
- getting in the sleep the itinerary allows.
It also means favoring familiar, easily digestible food once at the destination, since digestion slows and shifts during circadian disruption. None of this requires any special knowledge, and none of it should be skipped just because a trip feels short. Equally important is the scheduling decision made before the trip even starts: because of the challenges of adjusting across several time zones, it makes sense to weight travel plans toward extra days before competition.
For the next layer:
- Light exposure, timed to the direction of travel.
- Bright light earlier in the day helps shift the clock forward after eastward travel, while
- bright light later in the day helps shift it back after traveling west.
- Melatonin can support this process, but the timing matters:
- Low doses taken two to four hours before the target bedtime appear more useful than larger doses (>1mg).
- Caffeine, taken earlier in the day, can offset the daytime sleepiness that comes with jet lag, though it should be avoided in the hours before sleep, and a well-timed, easy training session can reinforce the same light-driven signal to the body’s internal clock.
For those focused on the extra 1%, a few targeted supplementation strategies to support immune function during a period when upper respiratory infection risk tends to climb.
- Vitamin C, taken in the range of 250mg to 1000 mg per day, has demonstrated some effectiveness in reducing URI symptoms among athletes,
- zinc is often considered alongside it as part of the same general immune-support strategy.
- Sucking on zinc lozenges might be an effective strategy to reduce airborne pathogens whilst flying.
- Probiotic supplementation, at a dose of roughly 10^10 live bacteria per day, is worth particular consideration in the two weeks before and during foreign travel, when exposure to pathogens and disrupted routines can heighten susceptibility to sickness.
- 1,000 IU per day of vitamin D is a reasonable supplementation target for those with tested Vitamin D insufficiency.
It's important to keep in mind that every supplement added to a regimen introduces more monetary expense and some degree of risk, so athletes should weigh that against the potential benefit rather than assuming more is automatically better. Opting for supplements that carry NSF Certified for Sport or Informed Sport certification is a practical way to remove one unnecessary source of uncertainty.
SUMMING IT UP
For an age-group athlete heading to an international race, the highest-value habits are the simplest ones. Because so much of race day performance is decided in the days leading up to it, travel planning deserves the same attention as training and nutrition. The athletes who come off a long haul ready to race are rarely the ones who are just “lucky”. They are the ones who treat hydration, sleep, and environmental adjustment with the same deliberateness they bring to their training plan.
Megan
References:
Erland LA, Saxena PK. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. J Clin Sleep Med. 2017 Feb 15;13(2):275-281. doi: 10.5664/jcsm.6462. PMID: 27855744; PMCID: PMC5263083.
Hatamiya, N., Holmes, K.E., Grosicki, G.J. et al. Optimizing Athlete Travel for Performance: A Scientific Blueprint for Athletes, Coaches, and Sports Medicine Staff. Sports Med 56, 1381–1403 (2026). https://doi.org/10.1007/s40279-026-02455-y